The impact of peritoneal dialysis-related peritonitis on mortality in peritoneal dialysis patients

Hongjian Ye1-3* MD, Qian Zhou1-4* MD, Li Fan1-3 MD & PhD, Qunying Guo1-3 MD & PhD, Haiping Mao1-3 MD & PhD, Fengxian Huang1-3 MD & PhD, Xueqing Yu1-3 MD & PhD, Xiao Yang1-3# MD & PhD

1 Department of Nephrology, The First Affiliated Hospital, Sun Yat-sen University, 58th, Zhongshan Road II, Guangzhou, 510080, China

2 Key Laboratory of Nephrology, Ministry of Health, Guangzhou, 510080, China

3 GuangdongProvincialKeyLaboratoryofNephrology, Guangzhou, 510080, China

4 Epidemiology Research Unit, The First Affiliated Hospital, Sun Yat-sen University, 58th, Zhongshan Road II, Guangzhou, 510080, China

* These authors contribute equally to this work.

# Correspondent author: Xiao Yang, MD, PhD.

Department of Nephrology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou 510080, China.

Phone: 0086-20-87755766-8843. Fax: 0086-20-87769673.

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Supplementary information

Supplementary Table S1. The PH assumption for the assessment of the relationship between peritonitis and overall mortality in peritoneal dialysis patients

Hazard ratio / 95% confident interval / P value
T_cov_# / 1.81 / 1.23-2.65 / 0.002
Peritonitis* / 0.14 / 0.04-0.50 / 0.003

Supplementary Table S2. The different models if considering only the first peritonitis in the Cox model for the study outcomes

Univariate model
HR (95% CI) / P value
All-cause mortality
Peritonitis* / 0.92 (0.71-1.19) / 0.526
Infection-related mortality
Peritonitis* / 2.91 (1.60-5.29) / <0.001
CV mortality
Peritonitis* / 0.80 (0.56-1.14) / 0.216

Note: Peritonitis* was considered only the first peritonitis in the Cox regression model.

Supplementary Table S3. Illustration for the follow-up time and how to parameterize peritonitis as a time-dependent for analysis in the COX regression model

Patient / Episodes of peritonitis / Follow-up period / Follow-up time (months) / Peritonitis status / Death
Start date / End date / Start time / End time / Length of follow-up
Patients with peritonitis
A / 0 / 13-May-2009 / 10-Jun-2010 / 0 / 13.0 / 13.0 / 0 / 0
A / 1 / 11-Jun-2010 / 31-Dec-2013 / 13.01 / 45.6 / 42.6 / 1 / 0
B / 0 / 21-Jul-2006 / 15-Oct-2006 / 0 / 2.8 / 2.8 / 0 / 0
B / 1 / 16-Oct-2006 / 26-Dec-2006 / 2.81 / 5.1 / 2.3 / 1 / 0
B / 2 / 27-Dec-2006 / 10-Oct-2007 / 5.11 / 14.5 / 9.4 / 1 / 0
B / 3 / 11-Oct-2007 / 26-Aug-2008 / 14.51 / 25.0 / 10.5 / 1 / 1
... / ... / ... / ... / ... / ... / ... / ... / ...
Patients free of peritonitis
C / 0 / 09-Dec-2009 / 31-Dec-2013 / 0 / 48.7 / 48.7 / 0 / 1

Note: For patient A, he experienced an episode of peritonitis on 11-Jun-2010, and he still survived at the end of the study (31-Dec-2013). Therefore, the immortal time for patient A is from 13-May-2009 to 10-Jun-2010. Patient B experienced 3 times of episode of peritonitis on 16-Oct-2006, 27-Dec-2006, and 11-Oct-2007, respectively, and experienced an death event on 26-Aug-2008. Similarly, the immortal time for patient B is from 21-Jul-2006 to 15-Oct-2006.

Supplementary Table S4. The interactionsbetween age and peritonitis for the assessment of the riskfor mortality

HR (95% CI) / P value
All-cause mortality
Peritonitis* / 2.70 (0.79-9.30) / 0.115
Age (per year increase) / 1.06 (1.05-1.08) / <0.001
Peritonitis*Age / 0.99 (0.98-1.01) / 0.578
Infection-related mortality
Peritonitis* / 105.4 (3.81-2919.7) / 0.006
Age ( per year increase) / 1.11 (1.06-1.15) / <0.001
Peritonitis*Age / 0.95 (0.93-1.04) / 0.064
CV mortality
Peritonitis* / 0.94 (0.15-5.76) / 0.944
Age ( per year increase) / 1.06 (1.05-1.08) / <0.001
Peritonitis*Age / 1.01 (0.98-1.04) / 0.473

Supplementary Table S5. The HRs of peritonitis for all-cause and infection-related mortality progressively by year in the COX proportional hazards models

Mean follow-up time (months ) / No. of deaths / Crude HR (95% CI) / P value / Adjusted HR (95% CI)# / P value
All-cause mortality
≤ 1 year / 11.3 ± 1.9 / 66 / 2.49 (1.40-4.44) / 0.054 / 1.12 (0.52-2.39) / 0.773
≤ 2 years / 20.7 ± 6.1 / 131 / 1.19 (0.75-1.88) / 0.465 / 0.80 (0.46-1.38) / 0.421
≤ 3 years / 27.7 ± 10.6 / 169 / 1.33 (0.92-1.93) / 0.130 / 1.00 (0.66-1.53) / 0.999
≤ 4 years / 32.0 ± 14.6 / 222 / 1.84 (1.37-2.47) / <0.001 / 1.51 (1.11-2.15) / 0.011
≤ 5 years / 34.3 ± 17.5 / 247 / 2.02 (1.53-2.66) / <0.001 / 1.74 (1.28-2.36) / 0.001
≤ 6 years / 35.5 ± 19.4 / 256 / 2.09 (1.60-2.74) / <0.001 / 1.84 (1.37-2.48) / <0.001
≤ 7 years / 35.9 ± 20.3 / 261 / 2.19 (1.68-2.85) / <0.001 / 1.95 (1.46-2.60) / <0.001
≤ 8 years / 36.0 ± 20.6 / 261 / 2.19 (1.68-2.85) / <0.001 / 1.95 (1.46-2.60) / <0.001
Infection-related mortality
≤ 1 year / 11.3 ± 1.9 / 9 / 3.53 (0.91-13.70) / 0.068 / 0.57 (0.06-5.25) / 0.616
≤ 2 years / 20.7 ± 6.1 / 16 / 2.25 (0.79-6.43) / 0.129 / 1.06 (0.26-4.32) / 0.932
≤ 3 years / 27.7 ± 10.6 / 26 / 3.26 (1.48-7.16) / 0.003 / 1.79 (0.69-4.66) / 0.230
≤ 4 years / 32.0 ± 14.6 / 37 / 5.21 (2.69-10.09) / <0.001 / 4.08 (1.83-8.77) / 0.001
≤ 5 years / 34.3 ± 17.5 / 41 / 5.68 (3.01-10.71) / <0.001 / 4.44 (2.14-9.22) / <0.001
≤ 6 years / 35.5 ± 19.4 / 43 / 5.55 (2.98-10.33) / <0.001 / 4.46 (2.19-9.09) / <0.001
≤ 7 years / 35.9 ± 20.3 / 46 / 6.01 (3.27-11.04) / <0.001 / 4.94 (2.47-9.86) / <0.001
≤ 8 years / 36.0 ± 20.6 / 46 / 6.01 (3.27-11.04) / <0.001 / 4.94 (2.47-9.86) / <0.001